The present invention relates to a disposable pull-on diaper for absorption and containment of bodily wastes.
Japanese Patent Application Disclosure Gazette (Kokai) No. Hei7-236650 discloses a disposable pull-on diaper including elastic members extending circumferentially of front and rear waist regions. Portions of these elastic members extending across a liquid-absorbent core of the diaper have an elongation less than 1.3 (i.e., substantially without any tension) and are secured to a backsheet of the diaper. Portions of the elastic members extending outward beyond transversely opposite side edges of the absorbent core have an elongation of 1.3 or higher and are secured also to the backsheet.
Japanese Patent Publication Gazette (Kokoku) No. Hei7-44945 discloses a disposable pull-on diaper including a plurality of elastic members extending circumferentially of front and rear waist regions across a liquid-absorbent core of the diaper so as to form a plurality of gathers in a zone overlying the absorbent core.
Japanese Patent Application Disclosure Gazette (Kokai) No. Hei9-84826 discloses a disposable pull-on diaper including a plurality of thread-like elastic members extending circumferentially of front and rear waist regions arranged so that these elastic members may be placed upon longitudinally opposite ends of a liquid-absorbent core of the diaper from outside the absorbent core.
The invention disclosed in the Japanese Patent Application Disclosure Gazette (Kokai) No. Hei7-236650 claims an advantageous effect such that the portions of the elastic members extending across the absorbent, core may be put substantially free from a tension so as to prevent the absorbent core from being wrinkled or position-shifted as the elastic members contract. However, the portions extending across the absorbent core can not function to press the absorbent core against the wearer""s body as they contract, since the portions are joined to the backsheet substantially without any tension. Accordingly, it is difficult for the diaper to assure a significant leakage preventing effect by a good fitting of the absorbent core to the wearer""s body.
Moreover, the invention is accompanied with a problem that the manufacturing process should include complicated steps of placing the elastic members partially in a tensioned state and partially in a non-tensioned state.
The invention disclosed in the Japanese Patent Publication Gazette (Kokoku) No. Hei7-44945 certainly describes an effect to place the liquid-absorbent core against the wearer""s body with a good fitting but does not disclose how to arrange these elastic members in the front and rear waist regions. Even if this problem is put aside, formation of gathers in the zone overlying the liquid-absorbent core not only may deteriorate a smooth touch of the diaper but also may form similar gathers on the absorbent core also. These gathers formed on the absorbent core may deteriorate its fitting to the wearer""s body and prevent body fluids from being rapidly absorbed.
The invention disclosed in the Japanese Patent Application Disclosure Gazette (Kokai) No. Hei9-84826 is certainly effective to restrain the longitudinally opposite ends of the absorbent core from being curved away from the wearer""s body. However, in order to widen a range over which the foresaid effect is obtained, the number of these elastic members must be correspondingly increased and properly arranged in the vicinity of the ends of the absorbent core. In consequence, the manufacturing process must be correspondingly complicated.
It is an object of the present invention to provide a disposable pull-on diaper improved to solve the foresaid various problems.
According to the present invention, there is provided a disposable pull-on diaper having a front waist region, a rear waist region and a crotch region therebetween, the diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between the topsheet and the backsheet, the front and rear waist regions being joined to each other along transversely opposite side edges thereof so as to form a waist-opening and a pair of leg-openings, the waist-opening being provided with a plurality of first elastic members and the leg-openings also being provided with elastic members, respectively, the elastic members extending under tension along peripheral edges of the waist-opening and leg-openings, wherein a plurality of second elastic members extend across the absorbent core at least in one of the front and rear waist regions between transversely opposite side edges of the waist region.
The disposable pull-on diaper of the present invention a plurality of second elastic members are such that any one of them presents a stretch stress lower than a stretch stress presented by any one of the first elastic members and extend across the absorbent core on an outer surface thereof with portions of the second elastic members which extend outward beyond the transversely opposite side edges of the absorbent core being secured to the backsheet and other portions thereof which extend between the transversely opposite side edges of the absorbent core being secured neither to the backsheet nor to the absorbent core.
Preferred but non-limiting embodiments of the present invention are enumerated hereunder.
(1) The second elastic members are secured to the backsheet only in the vicinity of zones in which the front and rear waist regions are joined to each other along their respective side edges.
(2) The backsheet is made of a thermoplastic synthetic resin film and the second elastic members are secured to the inner surface of the film.
(3) The backsheet comprises a thermoplastic synthetic resin film and a nonwoven fabric bonded to the outer surface of the film so that the second elastic members may be disposed between the film and the nonwoven fabric and secured to the outer surface of the film or the inner surface of the nonwoven fabric.
(4) The inner surface of the backsheet is joined to the outer surface of the absorbent core.
(5) The second elastic members are provided in the form of ribbons each having a width of 3xcx9c20 mm.
(6) The absorbent core has front and rear ends lying in the front and rear waist regions, respectively, and the second elastic members cover at least one of the front and rear ends inclusive of its vicinity in a direct or indirect manner.
(7) The absorbent core has a Gurley Stiffness Value of 0.5xcx9c2 g and the second elastic members present a total stretch stress of 100xcx9c230 gf.
(8) The crotch region is provided with a third elastic member extending under tension across the absorbent core in parallel to the second elastic members.